1. Field of the Invention
The present invention relates to a liquid crystal display device. The invention particularly relates to a liquid crystal display device configured to prevent from generation of short-circuiting between terminals or between bumps when the bump pitch in an IC driver is reduced in COG (Chip On Glass) connection.
2. Description of the Related Art
A conventional liquid crystal display device includes a TFT substrate having a pixel electrode, thin film transistors (TFT), etc. formed in a matrix; a counter substrate disposed in facing relation to the TFT substrate and having a black matrix, a overcoat layer, etc. formed at portions corresponding to the pixel electrodes of the TFT substrate; and liquid crystals put between the TFT substrate and the counter substrate. Images are formed by controlling the transmittance of light for every pixel by liquid crystal molecules.
Especially in medium- or small-sized liquid crystal display devices, there has been a tendency toward an increasingly finer structure, and the number of terminals has been increasing accordingly. On the other hand, in the IC driver for driving the liquid crystal display device, a shortening of the pitch between terminals (between bumps) permits the chip size to be reduced and promises a reduction in the cost of the IC driver. Thus, the terminal pitch has been reduced more and more in order to meet the demand from both the liquid crystal panel and the IC driver. When the terminal pitch becomes smaller, however, insulation between the terminals would become a problem.
JP-A-2008-28145 describes an approach for solving the problem that as the terminal pitch becomes smaller, the bumps of an IC driver may come to fail to enter (drop) into recesses of terminals. In the approach described in JP-A-2008-28145, the opening of the recess of each terminal is enlarged, and a lower-layer conductive film and an upper-layer conductive film are formed inside the enlarged opening so that the lower-layer conductive film is covered with the upper-layer conductive film. The configuration proposed in JP-A-2008-28145 makes it easy for the bumps of the IC driver to enter into the recesses of the terminals. In the recess, however, the width of the upper-layer conductive film would be enlarged, and the spacing between the terminals would be narrowed. Consequently, the problem of short-circuiting between the terminals still remains unsolved.